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Cassini’s grand finale will see orbiter plunge into Saturn

Cassini takes the plunge

ASA/JPL-Caltech/Space Science Institute

By Leah Crane

It’s an ending worthy of a Wagner opera. In September 2017– nearly 20 years after its launch – the Cassini spacecraft will crash into Saturn, sacrificing itself for the sake of the ringed giant’s potentially habitable moons.

Since Cassini went into orbit around Saturn in 2004, it has taken thousands of stunning images of the planet and its rings and moons. Over two extended missions, it has revealed new structures in the rings and observed Saturn’s weather in detail.

One of its most important discoveries was that small, icy Enceladus is venting plumes of water into space. That indicates this moon has a subsurface ocean, where conditions could be right to support life.

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And that is why Cassini must die. Despite all its hard work, the probe will run out of fuel next year. If it crashes into Enceladus, it could contaminate the pristine moon with either trace amounts of fuel or hitch-hiking Earth microbes. To avoid that, we will send Cassini to its demise in a mission fittingly dubbed the Grand Finale.

“The moon Enceladus could support life – and that is why Cassini must die”

First, Cassini will soar over a million kilometres above Saturn’s north pole and plummet past the outermost of its major rings, the F ring. Then it will plunge between the innermost rings and the planet, sampling the particles drifting from the rings into the atmosphere and measuring how much dust and ice they contain.

Next, Cassini will make 22 orbits through this region, one never explored before. Each taking only six days, they will yield maps of Saturn’s gravity and magnetic fields, giving us a window into its interior.

Finally, its legacy complete, Cassini will plunge into Saturn’s upper atmosphere and incinerate. But it will continue transmitting data right up until its final moments.

This article appeared in print under the headline “Cassini has its grand finale”